Vacuum-pump.



J. T. WILKIN.'

VACUUMl PUMP. APPL 10ATI0N FILM) AUG. 29,1908.

924,024. "Patent-evd. June .8, 1909..

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UNITED STATESIPATENT oFFronf vJOHN T. WILKIN, OF CONNERSVILLE, INDIANA, ASSIGNOR TO THE CONNERSVILLE BLOWER CO., OF GONNERSVILLE, INDIANA,

A CORPORATION OF INDIANA.

VAGUUMQUMP.

Specication of Letters-Patent.-

Patented June 8, 1909.

. Application filed August 20, 1908. Serial No. 449,389.

l To all 'whom it may concern: f

De it known that I, JOHN T. WrLK1N,la cltizen of the United States, residing at Connersville, 1n the county of Fayette and State of Indlana, have invented certain new and use ful Improvements in Vacuum-Pumps, of whlch the following is a specification.

- In the `operation of vlarge steam engine umts 1t 1s customary to maintain a vacuum 1n the condensing chamber and to continuously Withdraw the Water condensed therein.

In the use of pumps for thisr` urpose, wherein the dischar e from the con ensing chamber 1s directly into the passage the discharging Water flows', thereis a tendency for the discharged water to iiow backv into the vacuum pocket 4produced by the pump and thus' roduce a water hammer Which is very injurious to the mechanism. This is es ecially true when the .pump is of v the coactmg lobed impeller ty e wherein a f side of the impellers.I

Water sealis maintained .fon t e discharge The object of'my present invention is, therefore, to provlde means for preventing the injurious water hammer referred to and to rovide such other improvements and deta' s of construction as shall hereinafter be pointed out.

The` accompanying drawings illustrate my invention. i

' i Figure 1 is a side elevation, in partial aiiiall sectlon, of a pump built 1n accordance With -my invention, said pump being illustrated as a three-lobed coacting rotary impeller type;

Figi 2 is a section at right angles to' Fig. 1.v

to the particular form shown. The water" 'from a condensing chamber is introduced at'l -In the drawings, 10 indicates the, pump chamber in which aremounted the coacting lobed impellers 11 and 12, said impellers belng carried by shafts 13 and 14', respectively,

geared together foruniform motion inopposite directions by gears 'of the usual type con\ tained withincasing 15. In the drawings I have shown the lobed impellers providefd With three lobes but itis to be understood that my invention is not 'in any way limited through which l plate 18, and each of these chambers communicates, by an opening 19, with the im peller chamber l0 at a point below the axes of the impellers but above the normal water within they impeller chamber, and these Chambers l19 are connected by suitable con.-

nections 20 with the upper end of a condens- I lng chamber so that the gases within. the condensing chamber may i'low through the head#A plate-chambers 17 and the openings 19 into the suction side of th'e ump through a channel which is entirely distinct from the channel through which the condenser Water flows. In theoperation of such pump, a water seal is maintained in the upper side of the pump, (the discharge side being uppermost) as indicated by the line w Fig. 2 and, as the cessively carried from the suction side of the pump' tothe discharge side. In these displacement spaces there will be a small quantity ofwate'r`and a vacuum substantially equal to the vacuum contained in the condenser chamber so that, as soon as any particular displacement space is opened intothe discharge side of the pum ,there will be, because of the vacuum in t e displacement space, a backward rushof Water from the Water seal into the displacement space, thus causing a water hammer which is very inj urious and noisy. In order to prevent this action I provide air inlet passages 31, each of 4which is adapted to permit entrance of at-y mospheric pressure into each displacement space 30, after itfhas been cut off (by a lobe of the im eller) =fromthe suction side of the ump and before the displacement s ace is brought into communication with t e discharge side of the pump, so that, in an interimpellers rotate, 4displacement s aces 30, between adjacent lobes of the impe 1ers are sucmediate position, the displacement space is brought into communication Withthe atmosphere and .-the lvacuum relieved. In many instances, especially where the quantity of water is sma the air vent passagejmay be continuously o en, but under some circumstances i't is a visable to provide an autoi matic valve for opening and closing the air vent passage at proper times and I therefore show such a valve mechanism. In the form shoWnI have provided arotary valve 41, ar'- ranged at an intermediateY pointl in the alr' vent passage ,'31 and adapted to openl and -close the same, the passage being closed a l greater portion of the time but opened ,whenever a displacement space 30 is brought into proper intermediate position. In the form shown a half rotation of the valve 41 will the proportion of the gears being such as to open and close the valves in proper time.

` In order to protect the stuiiing boxes 51 from the influence of the vacuum on the suctionY side ofthe pump I form, in the end of each impeller, an annular groove 52, and this groove is connected by a groove 53 with the Adischarge side of the pump so that a water seal may be maintained in each groove 52 around the shaft of its impeller, in the manner described in my Patent No. 819,830.

I claim as my invention:-

1. The combination, in a vacuum pump of the lobed impeller type, of an air inlet passage leading into the pump chamber at a point to communicate with the displacement spaces after they are cut off from the suction side of the pump and before they are delivered to the discharge side of the pump.

2. The combination, in a vacuum pump of the lobed impeller type, of an air inlet passage leading into the pump chamber at a point to communicate with the displacement spaces after they are cut off from the suction side of the pump and before they are delivered to the discharge side of the pump, a'valve controlling said air inlet passage, and means for automatically opening and closing said valve.

3. The combination, in a vacuum. pump having a pair of coacting rotary lobed impellers and its discharge outlet uppermost, of

an air inlet passage leading into each side of the impeller chamber in position tocommunicate with the displacement spaces after they are separated from the suction side of the pump and before they are delivered to the discharge side of the pump.

4. The combination, in a pump having a pair of coacting rotary lobed im ellers and its discharge outlet uppermost, of an air inlet passage leading into each side of the inipeller chamber in position to communicate with the displacement spaces after they are separated from the suction side of the pump and before they are delivered to the discharge side of the pump, and valve mechanism for automatically. opening and closing said air inlet passages.

5. In a rotary pump of the rotary lobed impeller type having the usual inlet and discharge passages, a head-plate therefor having an air chamber formed therein and a conimunication between said air chamber and the impeller chamber at a point above the lowest line of movement of the impeller lobes.

6. A vacuum pump having a pair of coacting rotary lobed impellers mounted therein and having a water assage leading into the bottoni of the impeller chamber and an air passa e leading into the suction side of the impel er chamber at a point above the lowermost position of the impeller lobes.

In Witness whereof7 I have hereunto set my hand and seal at Connersville, Indiana,

. this 17th day of August,`A. D. one thousand nine hundred and eight.

J OIIN T. WILKIN. Witnesses:

C. R. HoUGHToN, G. W. ANCEED. 

